Tag Archives: health

Blind testing of bicycle fitting

Claims that getting a professional bike fit significantly improves riding comfort and speed and reduces overuse injuries seem suspicious – how can a centimetre here or there make such a large difference? A very wrong fit (e.g. an adult using a children’s bike) of course creates big problems, but most people can adjust their bike to a reasonable fit based on a few online suggestions.

To determine the actual benefit of a bike fit requires a randomised trial: have professionals determine the bike fit for a large enough sample of riders, measure and record the objective parameters of the fit (centimetres of seatpost out of the seat tube, handlebar height from the ground, pedal crank length, etc). Then randomly change the fit by a few centimetres or leave it unchanged, without the cyclist knowing, and let the rider test the bike. Record the speed, ask the rider to rate the comfort, fatigue, etc. Repeat for several random changes in fit. Statistically test whether the average speed, comfort rating and other outcome variables across the sample of riders are better with the actual fit or with small random changes. To eliminate the placebo effect, blind testing is important – the cyclists should not know whether and how the fit has been changed.

Another approach is to have each rider test a large sample of different bike fits, find the best one empirically, record its objective parameters and then have a sample of professional fitters (who should not know what empirical fit was found) choose the best fit. Test statistically whether the professionals choose the same fit as the cyclist.

A simpler trial that does not quite answer the question of interest checks the consistency of different bike fitters. The same person with the same bike in the same initial configuration goes to various fitters and asks them to choose a fit. After each fitting, the objective sizing of the bike is recorded and then the bike is returned to the initial configuration before the next fit. The test is whether all fitters choose approximately the same parameters. Inconsistency implies that most fitters cannot figure out the objectively best fit, but consistency does not imply that the consensus of the fitters is the optimal sizing. They could all be wrong the same way – consistency is insufficient to answer the question of interest.

Asking questions of yourself

To make better decisions, ask about all your activities “Am I doing this right? Is there a better way?” I would have benefited from considering such questions about many everyday tasks. For example, I brushed my teeth wrong (sawing at the roots) until late teens, brushed my teeth at the wrong time (right after a meal when the enamel is soft) until my 30s. I only learned to cut my own hair in my mid-20s, and this was the highest-return investment I ever made, because a hair clipper costs as much as a haircut, so pays for itself with the first use.

Peeling a kiwi with a spoon is far easier than slicing with a knife. All it took to learn this was one web search, but it required asking myself the question of whether I was peeling fruit optimally. Same for extracting the seed from an avocado.

Cracking the shell of a hard-boiled egg, making two holes at the ends and blowing air under the membrane before peeling is another trick I wish I had known earlier.

Microwaved food is cooler in the centre, so to avoid scalding one’s mouth, it is helpful to start eating it from the middle. Cooked food left in a covered cooking pot or transferred to a storage container while still mildly hot does not go bad at room temperature for several days – doing this experiment required posing this hypothesis. Drinking without touching the bottle with one’s mouth turns out to be quite easy and is widespread in India.

Only after learning to drive did I start meaningfully using gears on a bicycle, and it took about 15 years more to start shifting approximately correctly (pedalling cadence 60-100 rotations per minute, downshifting before stopping, avoiding cross-geared riding). Similarly for basic bike maintenance like cleaning and oiling the chain, selecting the appropriate front and rear tire pressure given one’s weight and tire widths. Seat height is one thing I figured out early, but not handlebar height.

As a teenager, I would have benefited from asking myself whether I was overtraining, whether my nutrition was reasonable, how soon to return to training after various injuries and whether to seek medical assistance with these. Questioning the competence of coaches and doing a simple web search for sports medicine resources would have prevented following some of their mistaken advice.

Sometimes asking yourself the question reveals that you are already doing the task correctly. On the internet, people claim that they do not use shampoo, just water, and their hair stays clean-smelling and more lush than using detergent. An experiment not to use shampoo was a failure for me, causing greasy hair and lots of dandruff after a few days. The optimality of shampoo may depend on individual scalp and hair characteristics. On the other hand, a single-blade disposable razor and cold water give me a better shave than multi-bladed fancy brands with foam (that get clogged), and the disposable razor stays sharp enough for a month or two of everyday shaving.

When going to teach, it may be worth asking whether the room is the correct one, even if some students show up and the room is free, because once in this situation I was in a room with the right label, but in the wrong building.

On the other hand, constantly doubting oneself is unhealthy and unhelpful. If enough evidence points one way, then it is time to make up one’s mind.

Why princesses and princes are described as attractive

The bards and scribes who recorded events for posterity received their income essentially in the form of tips from the rulers and the rich, so had an incentive to flatter, describing their patrons as more attractive, virtuous, brave, etc than they really were.

In addition to the exaggeration of their actual attractiveness in reports that have reached us, the children of the wealthy probably really were more beautiful than the poor. Richer youth were better fed and cared for, thus had fewer developmental abnormalities (e.g. bent legs from calcium deficiency) and diseases. The poor were malnourished, lived in dirty conditions and were subject to violence, therefore were more likely stunted, stank and had skin diseases, missing teeth and scars. The latter two distinctions in looks have to a lesser extent lasted to the present day, for the same reason.

Attractiveness consists of the visual, audible and olfactory signals of a fit mate (healthy, fertile conspecific), because organisms evolved to consider fit mates attractive. In times when most people were malnourished and diseased, a well fed and healthy rich person would have been much fitter than most, thus a preferred sexual partner for others.

On the other hand, conditional on surviving to adulthood, the poor likely had better immune-related genes, because they were under stronger selection pressure. Poorer people also experienced more infections, thus acquired stronger immunity to more diseases if they survived. Then conditional on equal looks, a person from a poorer background would have been a fitter mate. Also, the ruling class intermarried to keep wealth in the family, so were inbred (hereditary diseases among European royalty are an example consequence). For these two reasons, it is not surprising that the rulers and the rich found some poor people sexually attractive, specifically the outwardly healthiest-appearing among those who reached maturity.

Multifunctional layered clothing

Hiking websites recommend wearing layers, because these make adjusting between warm and cold weather or uphill and downhill walking simple. One thick garment would only work for cold, but taking it off when it gets too hot may leave only too thin clothing.

The same principle of layers applies for everyday clothes. My office is 12 degrees in winter mornings, so I wear two pairs of pants, sometimes two vests and a fleece. Instead of one thick pair of pants that would only suit cold temperatures, thin pants can be worn singly in warm weather and doubled up in cold.

For cycling in the cold, shorts can be worn under long athletic slacks. This principle should also work for hats – two thin fleece ski caps instead of one thick, but I have not tested it. Similarly, two pairs of socks. Although, just like with thick socks, if doubled socks make the shoes fit too tightly, then the reduced circulation increases the cold feeling.

Toe warmer making instructions on the internet suggest using the cut-off front parts of old socks. A more multifunctional option is to roll back existing socks halfway, so both the toe and the ankle part of the sock cover the toes, as in the following image.

Cut socks only work as toe warmers, but rolled-back socks can be used year round.

Blind testing of clothes

Inspired by blind taste testing, manufacturers’ claims about clothes could be tested by subjects blinded to what they are wearing. The test would work as follows. People put clothes on by feel with their eyes closed or in a pitch dark room and wear other clothes on top of the item to be tested. Thus the subjects cannot see what they are wearing. They then rate the comfort, warmth, weight, softness and other physical aspects of the garment. This would help consumers select the most practical clothing and keep advertising somewhat more honest than heretofore. For example, many socks are advertised as warm, but based on my experience, many of them do not live up to the hype. I would be willing to pay a small amount for data about past wearers’ experience. Online reviews are notoriously emotional and biased.

Some aspects of clothes can also be measured objectively – warmth is one of these, measured by heat flow through the garment per unit of area. Such data is unfortunately rarely reported. The physical measurements to conduct on clothes require some thought, to make these correspond to the wearing experience. For example, if clothes are thicker in some parts, then their insulation should be measured in multiple places. Some parts of the garment may usually be worn with more layers under or over it than others, which may affect the required warmth of different areas of the clothing item differently. Sweat may change the insulation properties dramatically, e.g. for cotton. Windproofness matters for whether windchill can be felt. All this needs taking into account when converting physical measurements to how the clothes feel.

Seasonings may reduce the variety of diet

Animals may evolve a preference for a varied diet in order to get the many nutrients they need. A test of this on mice would be whether their preference for different grains is negatively autocorrelated, i.e. they are less likely to choose a food if they have eaten more of it recently.

Variety is perceived mainly through taste, so the mechanism via which the preference for a varied diet probably operates is that consuming a substance repeatedly makes its taste less pleasant for the next meal. Spices and other flavourings can make the same food seem different, so may interfere with variety-seeking, essentially by deceiving the taste. A test of this on mice would flavour the same grain differently and check whether this attenuates the negative autocorrelation of consumption, both when other grains are available and when not.

If seasonings reduce variety-seeking, then access to spices may lead people to consume a more monotonous diet, which may be less healthy. A test of this hypothesis is whether increased access to flavourings leads to more obesity, especially among those constrained to eat similar foods over time. The constraint may be poverty (only a few cheap foods are affordable) or physical access (living in a remote, unpopulated area).

A preference for variety explains why monotonous diets, such as Atkins, may help lose weight: eating similar food repeatedly gets boring, so the dieter eats less.

Adapting to a low-salt diet is quick

Overconsumption of salt is a significant public health problem. People are reluctant to reduce the saltiness of their food, because it would taste bland. Eventually, preferences adjust so that a diet without added salt tastes normal and salted foods are perceived as too salty. The only question is how quickly tastes adapt.

My experience of stopping adding any salt to my food was that the bland taste lasted less than 3 days, after which I had fully adjusted to the new reduced level of saltiness. An easier way to adapt may be to gradually reduce the amount of added salt, as opposed to suddenly cutting off all of it, as I did. In that case, there may be no perceived taste difference, especially if the reduced salt is accompanied with increased amounts of other seasoning, like pepper. Given the smallness of the adjustment cost and the health benefit of cutting salt consumption, doing it is a clear and easy win.

Chair material should be breathable

Strangely enough, fancy office chairs are often upholstered in leather or other non-breathable material. After an hour or so, sitting in them gets uncomfortable because the moisture does not evaporate from the skin that is separated from the chair only by some cloth. However, people usually sit in office chairs for hours at a time, and I doubt that the chairs are designed to deliberately provide some discomfort to encourage users to occasionally stand up for health reasons. Especially in a hot climate when the air conditioning may break down or just be too weak, a breathable chair would make much more sense. Making a mesh chair is simple: stretch a breathable fabric on the chair frame. The small holes in the fabric let moisture evaporate from the surface. A mesh chair is probably cheaper to manufacture than a leather-upholstered one.

A reason for using leather may be to signal wealth by using a material associated with expensiveness.

Modern synthetic meshes are as durable as leather for practical purposes, because sitting in a chair is not a high-wear use.

How to stop crutches from clicking

Adjustable-length metal crutches click with each ground contact and lifting, which some people find annoying. The reason for the clicks is that the push button used to adjust the length of the crutch is not snug in its hole, but pushes against the top of its hole when the crutch is pressed against the ground and against the bottom of the hole when the crutch is lifted.

The push button length adjustment system consists of two pipes inside each other, with holes in the outer pipe and a spring-loaded button on the inner one. Pushing the button in allows the pipes to slide relative to each other. When the button is released and pops out into a hole, it locks the pipes together. Similar push button systems are used to adjust the handle length of rolling luggage and the weight stacks of gym equipment.

To silence the clicks, the button should push against the same side of the hole at all times, which can be achieved by adding one spring. The spring should pull the inner pipe of the adjustable part of the crutch in the direction of shortening the crutch, i.e. the same direction as ground contact. Then the button always stays in contact with the same side of its hole instead of alternately hitting the two opposing sides. The reason the spring should pull in the same direction as ground contact is that the upward force on the adjustable inner pipe when the crutch bears the weight of the user is much greater than the downward force of the weight of the inner pipe when the crutch is lifted. Thus it is easier to overcome the downward force using a spring.

A homemade version of the spring is to tie a rubber band under tension to above and below the adjustment button. A bungee cord or bicycle inner tube would work as well.

The length adjustment of the crutch with a spring would be similar to that of an office chair – automatic in one direction, but requiring force in the other. When the button is pushed, the crutch shortens automatically by one hole. To lengthen the crutch, one has to push the button in and then pull the crutch in two opposing directions.

Pill testing, placebos and illegal market efficiency

Testing illegal drugs for the active ingredient differs from testing for poisonous adulterants. Both tests have opposite effects on drug use before and after buying. After the pill has been purchased, testing reduces use, because sometimes the drug fails the test, whether correctly or not, and is discarded. Before purchase, the option to test for and avoid adulterated or inactive drugs reduces the buyer’s risk, thus increases use.

In the longer term, testing benefits the dealers of purer, more predictable and less toxic drugs, putting some suppliers of fakes out of business. Pill predictability reduces overdoses – a health effect similar to lower toxicity. If old drugs can be tested, but new ones not, then buyers experiment less and the incentive to invent new narcotics decreases.

The avoidance of poisonous adulterants is good for public health, but purer pills not necessarily so. Inactive drugs undermine consumer confidence in the illegal market, reducing use, prices and casual purchases. Trust then requires a long-running relationship with the seller, which has multiple benefits. It motivates dealers to care about the health of their loyal customers, simplifies policing and gives researchers and social workers better long-term access to the at-risk population.

One claimed benefit of party drugs is that they reduce anxiety, increase the user’s confidence and social interaction, thus improving mental health. Evidence from psychiatric medicines suggests that many such benefits are due to the placebo effect. Users are quite inaccurate in estimating the purity of ingested drugs, and factors like price and place of purchase strongly influence their perception of purity. The price per pure gram is negatively related to purity in some markets, further supporting the placebo interpretation. If inactive pills boost confidence similarly to illegal drugs, then there is a clear case for flooding the market with harmless placebos. The availability of pill tests for the active ingredient reduces this opportunity to make the illegal market inefficient. Tests for toxic adulterants, however, actually favour harmless placebos.